Tuyển tập các báo cáo nghiên cứu về y học được đăng trên tạp chí y học Radiation Oncology cung cấp cho các bạn kiến thức về ngành y đề tài: Radiobiological evaluation of forward and inverse IMRT using different fractionations for head and neck tumours. | Ferreira et al. Radiation Oncology 2010 5 57 http content 5 1 57 RADIATION ONCOLOGY RESEARCH Open Access Radiobiological evaluation of forward and inverse IMRT using different fractionations for head and neck tumours 1 2 2 2 Brigida C Ferreira Maria do Carmo Lopes Josefina Mateus Miguel Capela Panayiotis Mavroidis Abstract Purpose To quantify the radiobiological advantages obtained by an Improved Forward Planning technique IFP and two IMRT techniques using different fractionation schemes for the irradiation of head and neck tumours. The conventional radiation therapy technique CONVT was used here as a benchmark. Methods Seven patients with head and neck tumours were selected for this retrospective planning study. The PTV1 included the primary tumour PTV2 the high risk lymph nodes and PTV3 the low risk lymph nodes. Except for the conventional technique where a maximum dose of Gy was prescribed to the PTV1 Gy Gy and Gy were prescribed respectively to PTV1 PTV2 and PTV3. Except for IMRT2 all techniques were delivered by three sequential phases. The IFP technique used five to seven directions with a total of 15 to 21 beams. The IMRT techniques used five to nine directions and around 80 segments. The first IMRT1 was prescribed with the conventional fractionation scheme of Gy per fraction delivered in 39 fractions by three treatment phases. The second IMRT2 simultaneously irradiated the PTV2 and PTV3 with Gy and Gy in 28 fractions respectively while the PTV1 was boosted with six subsequent fractions of Gy. Tissue response was calculated using the relative seriality model and the Poisson Linear-Quadratic-Time model to simulate repopulation in the primary tumour. Results The average probability of total tumour control increased from 38 with CONVT to 80 with IFP to 85 with IMRT1 and 89 with IMRT2. The shorter treatment time and larger dose per fraction obtained with IMRT2 resulted in an 11 increase in the .
